7 * Userspace RCU - sys_futex/compat_futex header.
9 * Copyright 2011-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 #include <urcu/config.h>
27 #include <urcu/syscall-compat.h>
33 #if (defined(__linux__) && defined(__NR_futex))
35 /* For backwards compat */
36 #define CONFIG_RCU_HAVE_FUTEX 1
40 #include <urcu/compiler.h>
41 #include <urcu/arch.h>
43 #elif defined(__FreeBSD__)
45 #include <sys/types.h>
58 * sys_futex compatibility header.
59 * Use *only* *either of* futex_noasync OR futex_async on a given address.
61 * futex_noasync cannot be executed in signal handlers, but ensures that
62 * it will be put in a wait queue even in compatibility mode.
64 * futex_async is signal-handler safe for the wakeup. It uses polling
65 * on the wait-side in compatibility mode.
67 * BEWARE: sys_futex() FUTEX_WAIT may return early if interrupted
71 extern int compat_futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
72 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
);
73 extern int compat_futex_async(int32_t *uaddr
, int op
, int32_t val
,
74 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
);
76 #if (defined(__linux__) && defined(__NR_futex))
78 static inline int futex(int32_t *uaddr
, int op
, int32_t val
,
79 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
81 return syscall(__NR_futex
, uaddr
, op
, val
, timeout
,
85 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
86 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
90 ret
= futex(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
91 if (caa_unlikely(ret
< 0 && errno
== ENOSYS
)) {
93 * The fallback on ENOSYS is the async-safe version of
94 * the compat futex implementation, because the
95 * async-safe compat implementation allows being used
96 * concurrently with calls to futex(). Indeed, sys_futex
97 * FUTEX_WAIT, on some architectures (mips and parisc),
98 * within a given process, spuriously return ENOSYS due
99 * to signal restart bugs on some kernel versions.
101 return compat_futex_async(uaddr
, op
, val
, timeout
,
108 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
109 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
113 ret
= futex(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
114 if (caa_unlikely(ret
< 0 && errno
== ENOSYS
)) {
115 return compat_futex_async(uaddr
, op
, val
, timeout
,
121 #elif defined(__FreeBSD__)
123 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
124 const struct timespec
*timeout
,
125 int32_t *uaddr2
__attribute__((unused
)),
126 int32_t val3
__attribute__((unused
)))
129 void *umtx_uaddr
= NULL
, *umtx_uaddr2
= NULL
;
130 struct _umtx_time umtx_timeout
= {
131 ._flags
= UMTX_ABSTIME
,
132 ._clockid
= CLOCK_MONOTONIC
,
137 /* On FreeBSD, a "u_int" is a 32-bit integer. */
138 umtx_op
= UMTX_OP_WAIT_UINT
;
139 if (timeout
!= NULL
) {
140 umtx_timeout
._timeout
= *timeout
;
141 umtx_uaddr
= (void *) sizeof(umtx_timeout
);
142 umtx_uaddr2
= (void *) &umtx_timeout
;
146 umtx_op
= UMTX_OP_WAKE
;
153 return _umtx_op(uaddr
, umtx_op
, (uint32_t) val
, umtx_uaddr
,
157 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
158 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
160 return futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
163 #elif defined(__CYGWIN__)
166 * The futex_noasync compat code uses a weak symbol to share state across
167 * different shared object which is not possible on Windows with the
168 * Portable Executable format. Use the async compat code for both cases.
170 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
171 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
173 return compat_futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
176 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
177 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
179 return compat_futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
184 static inline int futex_noasync(int32_t *uaddr
, int op
, int32_t val
,
185 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
187 return compat_futex_noasync(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
190 static inline int futex_async(int32_t *uaddr
, int op
, int32_t val
,
191 const struct timespec
*timeout
, int32_t *uaddr2
, int32_t val3
)
193 return compat_futex_async(uaddr
, op
, val
, timeout
, uaddr2
, val3
);
202 #endif /* _URCU_FUTEX_H */
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